Contrary to popular belief, LED replacement lamps don’t last forever. The last longer than incandescents, but they do go after a while. Probably half of the LEDs I have used have eventually failed. I will never again buy Cree bulbs, I haven’t had good luck with them.
Contrary to popular belief, LED lamps aren’t all “instant on”. I have one that takes about 1/2 second to light up. I bought that one as an experiment to see if I liked it. I didn’t.
Both LED and CFL bulbs produce RF interference (it varies according to make). Incandescent bulbs don’t have that problem, and I will continue to use them in certain locations as long as I can.
CFL bulbs have a weird character to their light that shows up on the lacquered brass case of a clock that I own. It’s hard to describe, but it looks sort of like it’s covered by rainbow swirls when illuminated by a CFL. I still have a few of them around, as they die, they will be replaced by LEDs.
They have a discrete spectrum, which you can see just by holding a diffraction grating close to your eye, and looking to the top or bottom, away from the light. You will see a sequence of distinct monochromatic images of the exposed portion of the bulb. A deep violet, a deep blue, an aquamarine, a green, then a fainter spread of yellow to red, with a distinct bright red image embedded in it.
I just checked this with my diffraction grating which I keep handy at all times :-)
We recently got LED streetlights, and their spectrum is broken, but has long continuous ranges. It's still qualitatively different from the household incandescent spectrum, which is continuous, and peaks in the infrared, which gives it a bright red tail. I can still see plenty of green, blue, and violet, though. ( Spectral violet looks "purple" to me, although technically purple is a mixture of spectral red and blue. )